I’m using Propulsion and bought Woocommerce’s Catalog Visibility Options extension (customizes prices / purchase visibility). I’ve made price visibility and purchase function enabled only for logged in users. Tried testing it out and this came up at Checkout:

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Basically, my website started loading on top of my Checkout page, and I couldn’t click on the Place Order button. When I went back to check my Cart, I’ve been logged out and was asked to log in again. I logged in again and repeat and the Checkout still came out like that.

I’ve also installed the ff. plugins / extensions. Would they have something to do with this?

You can try disabling the other plugins you have active and testing the extensions functionality again. I’m not familiar with Catalog Visibility Options and we don’t have access to the premium extensions in general to test on unfortunately so I’m the best we can do is take a look at your site live and see if its something we can see up front.